Process for the preparation of viscose



Patented May 26, 1931 1 UNETED STATES PATENT GFFICE JACQUES MARCBERNARD, F PABIw, FRANCE PROCESS FOR THE IREPABATIQN OF VISCOSE NoDrawing. Application filed May 27, 1927, Serial No. 194,851, and inFrance June 24, 1 926.

In the known process for the manufactirely saturated. The carbondisulphide may ture of the cellulose compounds designated be employedin'the form of liquid or vapor, as viscose which are employed for themanor a mixture of the two. ufacture of films, textile filaments and Theexcess of the carbon disulphide is 5 threads, and the like, thecellulose is treated discharged through an orifice at the bottom,successively by caustic soda (NaOH) and and it is afterwards removed, ifnecessary, by carbon disulphide for the obtainment of by the use of avacuum for a few moments a cellulose compound which is soluble in only,so as not to dry the cellulose. water. When it is found that thecellulose has 19 The present invention relates to an imbeen wellsaturated with the carbon disulproved process for the manufacture ofVisphide, I add 100200 liters of caustic soda cose in which thecellulose is first treated, solution which contains-with a certain exina closed rotatable cylinder, with carbon cess-the amount of soda(NaOI-I) which disulphide, then adding a solution of causis required toform the xanthate, and the 15 tic soda (NaOI-I). A vacuum is thenproapparatus is rotated more slowly until the duced for the removal andthe recovery of xanthate is completely formed. the excess of carbondisulphide. After a. If necessary, a vacuum is produced during shorttime there is formed a pasty subthe whole or the last half of thislatter stance, soluble in water, which is then operation. a

20 t t d b th known th d The resulting product is supplied to the Inthis manner the labor and apparatus mixer, and the proper amount of sodarequired in the known processes for prepar- (NaOH) and water is added,so as to obtain ing, grinding and ripening the alkali-celluafter thechurning operation a percentage lose compound are eliminated. A great ofcellulose as well as aviscosity which co-reconomy of soda is thusobtained and a conresponds to the use which is to be made of thesiderable part of the carbonate formation vlscose. I in the alkali bathswhich are exposed to the In a modification of the said process, I air iseliminated. Further the formation of may employ a closed mixer which isarhemi-celluloses which may be produced from ranged for the supply ofthe carbon disulco the soaking operation to the end of the phide and forthe production of a vacuum alkali-cellulose ripening is obviated; thetherein; I perform all of the aforesaid operformation of sulphoearbonateof sodium is ations in the said mixer, and the speed of reduced, and theloss of cellulose, which rotation is varied according to the differenttakes place due to the incomplete action stages of the operation.

S5 of the disulphide upon the alkali-cellulose I may further combine thetwo aforesaid 35 when the latter is not sufliciently ripened, is methodsby causing the cellulose to absorb eliminated. the carbon disulphide inthe churning ap- By way of example I may operate in the paratus and bythen placing the resulting following manner, it being understood thatsubstance, as a whole or by successive frac- QD the proportions whichare indicated below tions, in the mixer which contains the causare notof a limitative nature. tic soda solution. a

I place in a churning apparatus of 600 In certain of the known methodsfor the liters capacity, 50 kgs. of cellulose containmanufacture ofviscose,the cellulose is first ing 10 per cent of moisture, representedfor mercerized by the caustic soda (NaOI-I) 4.3 instance by sheets ofwood paste cut into and this is followed by a washing with pieces having10 to 20 cm. on a side, or I water which eliminates the soda used inniay employ cellulose of another form such this treatment as well as thehemi-celluloses. as cotton or the like. The apparatus is set 'Thecellulose thus washed is then subjected in rotation, and I then addcarbon disulto the several treatments in current use, i. e.

so hide in excess, so that the cellulose is enit is soaked in a causticsoda solution,

pressed, torn into fragments and allowed to ripen, these operationspreceding the treatment by the carbon disulphide.

The process according to this invention is also applicable to kinds ofcellulose which have been subjected to this preliminary treatment, i. e.soaking in a caustic soda solution followed by a washing with Water, andafter these operations, the cellulose is treated according to my abovesaid process.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A process for the manufacture of liquid viscose which consists inimpregnating cellulose with carbon disulphide, adding thereto a solutionof caustic soda, allowing the caustic soda to transform the celluloseinto liquid Xanthate of cellulose, and diluting in an aqueous bath tothe viscosity of the viscose to be produced, all these operations beingperformed at ordinary temperature.

2. A process for the manufacture of liquid viscose which consists inimpregnating cellulose with carbon disulphide, producing a vacuum forthe removal and the recovery of the excess of carbon disulphide, addingto the impregnated cellulose a solution of caustic soda, allowing thecaustic soda to transform the cellulose into liquid Xanthate ofcellulose, and diluting in an aqueous bath to the viscosity of theviscose to be produced, all these operations being performed at ordinarytemperature.

A process for the manufacture of liquid viscose which consists inimpregnating cellulose with carbon disulphide in. a rotating closedcylinder, in then adding in said cylinder a solution of caustic soda,stirring said cellulose in said caustic soda to transform said celluloseinto liquid Xanthate of cellulose, and diluting in an aqueous bath tothe viscosity of the viscose to be produced, all these operations beingperformed at ordinary temperature.

4-. A process for the manufacture of liquid viscose which consists inimpregnating inercerized cellulose with carbon disulphide, addingthereto a solution of caustic soda, a1- lowing the caustic soda totransform the cellulose into liquid Xanthate of cellulose, and dilutingin an aqueous bath to the viscosity of the viscose to be produced, allthese operations being performed at ordinary temperature.

A process for the manufacture of liquid viscose which consists inimpregnating cellulose with carbon disulphide, adding thereto a solutionof caustic soda, allowing the caustic soda to transform the celluloseinto liquid Xanthate of cellulose, producing a vacuum for the removaland the recovery of the excess of carbon disulphide, and diluting in anaqueous bath to the vis- JACQUES MARC BERNARD.

produced, all these performed at ordinary signed my

